1. Field of the Invention
The present invention relates to a notification control device for notifying the situation of an event by controlling characteristics of a sound emitted from a speaker, its system, its method, its program, a recording medium storing the program, and a travel support device.
2. Description of Related Art
Art for modifying characteristics of a sound emitted from a speaker to notify an event has been known. It includes various known configurations such as an alarm clock adapted to control an alarm sound emitted from a speaker by, for example, increasing the volume of the alarm sound or changing the alarm sound from an intermittent sound to a continuous sound as a predetermined time, which may be a waking time, approaches. Reference 1: Japanese Patent Laid-Open Publication No. Hei. 9-211158 and Reference 2: Japanese Patent Laid-Open Publication No. Hei. 10-332854 discloses such techniques.
More specifically, Reference 1 discloses an arrangement adapted to selectively modify the base current and the collector current of a transistor for amplifying the electric current applied to a speaker by adding an external circuit to a voice synthesizing IC for outputting an alarm sound and controlling all the resistance from the input terminal to the output terminal of the externally added circuit by means of the voice synthesizing IC. Then, the volume of the alarm sound is changed by selectively changing the base current and the collector current of the transistor by means of the externally added circuit.
Reference 2 discloses an arrangement adapted to select one of a plurality of different waveforms for the drive voltage applied to a motor from a drive voltage waveform generating section capable of outputting the plurality of drive voltage waveforms by using a switching section. Then, the motor is driven by a predetermined drive voltage waveform at a preset time so as to control the output form, i.e., the sounding form of an alarm sound of an alarm sound generating section for generating the alarm sound.
However, with the arrangements of above-described References 1 and 2 for changing the volume of the alarm sound and changing the sounding form of the alarm sound, the position of the source of the sound that is heard and recognized at a user position does not change and, for example, it is difficult to judge the urgency or the significance of the sound notification simply by hearing the sound. Particularly, if different notifications are given from a plurality of sound sources, it will be difficult for the user to judge which notification is most urgent or significant.
Additionally, if different notifications, e.g., an alarm for gas leakage and an alarm of an alarm clock, are given simultaneously, it is difficult for the user to judge which of the notifications is more urgent or significant. Then, the user may not be able to respond appropriately to the notifications.